74 MEMOIRS OF THE CARNEGIE MUSEUM 
latter are taken from the manus of Brontosawrus, a detailed account of the structure 
of which was recently published by the writer.’ 
The Supposed Clavicles. —In my original description of Diplodocus carnegii I 
figured and described a peculiar bone which I then considered as a clavicle, though 
at the same time expressing some doubt as to its real nature. Fortunately we have 
found associated with another skeleton (No. 662) of Diplodocus a second and more 
complete clavicle? shown here in Fig. 2, a, b. The present specimen is somewhat 
incomplete at the bifid extremity, the smaller branch having been broken away, the 
opposite end is complete, somewhat expanded and spatulate as shown in the 
figures. The spatulate portion has a length of 265 millimeters, a maximum breadth 
of 75 millimeters and an average thickness of about 24 millimeters. 
The entire length of the bone measuring along the are of that portion of the 
circle which it describes is 620 millimeters. Between the expanded portion and the 
forked extremity the bone is irregularly elliptical or subcireular in cross-section. 
This bone is asymmetrical and is to all appearances a paired bone. In neither 
instance have we as yet secured its opposite, though this is still possible with that 
one now being considered, a considerable portion of the skeleton still remaining to 
be unearthed. Just at the point where the rounded shaft passes into the flattened, 
spatulate extremity there is on one side a shallow groove running obliquely across 
the surface of the bone. This groove has the appearance of having been formed by 
the overlapping edge of a coracoid or sternal. The flattened spatulate extremity pre- 
sents aslightlyrugose, fibrous surface as though it had been imbedded in cartilagin- 
ous or muscular tissue, and this together with the bifid nature of the other extremity 
has suggested the possibility that the bone might be an os penis; in which case the 
bifid extremity would be the distal end and the flattened the proximal extremity. 
Against the probability of this assumption however, the marked asymmetry of the 
bone offers a potent argument and I am still strongly inclined to consider it a clavicle 
as which it might very readily have functioned. Although clavicles have not here- 
tofore been recognized in the Dinosauria there would seem no good reason for sup- 
posing that they were not present in some members of that group. A clavicle of 
the size and form of the element under discussion, if attached to the anterior edge 
of the broadly expanded sternals, coracoid and prescapula, could not have failed in 
giving additional strength and rigidity to this portion of the skeleton. 
The Anterior Cervicals. — In my former paper, owing to the incomplete nature of 
ceryicals 3, 4, 5, they were figured as without cervical ribs; later discoveries (No. 662) 
demonstrate that ribs were present on all these vertebree and they are so shown in 
the accompanying restoration (Plate F). 
*See Science, N. S., Vol. XIV., pp. 1015-1047; and Annals Carnegie Museum, Vol. I., pp. 356-376. 
